The comet assay allows for the detection of DNA damage in any accessible cell population and a molecular definition of the DNA damage is possible with adaptation of the basic assay. Trevigen has developed a platform for the comet assay consisting of a specially treated glass support, promoting the adherence of agarose, with demarcated sample application areas. This phase I proposal describes the development and validation of a higher-throughput format for comet assay. The system will consist of a support with multisample application areas pretreated for direct sample application for use with standard microscope platforms and current data analysis packages. The prototype will be validated for both the standard and the modified comet assay. The long term objective is to provide a rapid, cheap, standardized, and validated assay for the monitoring of genotoxicity of drugs or other treatments. The assay can be applied to both cells in culture for assessment of drugs very early in the screening process, and to samples obtained from animal tissue for specific organ toxicity monitoring of drug metabolites. [unreadable] [unreadable]